title: Effect of chronic activity-based therapy on bone mineral density and bone turnover in persons with spinal cord injury.
abstract: OBJECTIVE
  Osteoporosis is a severe complication of spinal cord injury (SCI). Many exercise modalities are used to slow bone loss, yet their efficacy is equivocal. This study examined the effect of activity-based therapy (ABT) targeting the lower extremities on bone health in individuals with SCI.
  
  
  METHODS
  Thirteen men and women with SCI (age and injury duration = 29.7 ± 7.8 and 1.9 ± 2.7 years) underwent 6 months of ABT. At baseline and after 3 and 6 months of training, blood samples were obtained to assess bone formation (serum procollagen type 1 N propeptide (PINP) and bone resorption (serum C-terminal telopeptide of type I collagen (CTX), and participants underwent dual-energy X-ray absorptiometry scans to obtain total body and regional estimates of bone mineral density (BMD).
  
  
  RESULTS
  Results demonstrated significant increases (p < 0.05) in spine BMD (+4.8 %; 1.27 ± 0.22-1.33 ± 0.24 g/cm(2)) and decreases (p < 0.01) in total hip BMD (-6.1 %; 0.98 ± 0.18-0.91 ± 0.16 g/cm(2)) from 0 to 6 months of training. BMD at the bilateral distal femur (-7.5 to -11.0 %) and proximal tibia (- 8.0 to -11.2 %) declined but was not different (p > 0.05) versus baseline. Neither PINP nor CTX was altered (p > 0.05) with training.
  
  
  CONCLUSIONS
  Chronic activity-based therapy did not reverse bone loss typically observed soon after injury, yet reductions in BMD were less than the expected magnitude of decline in lower extremity BMD in persons with recent SCI.
authors.affiliation: Department of Kinesiology, California State University, San Marcos, 333. S. Twin Oaks Valley Road, UNIV 320, San Marcos, CA, 92096-0001, USA, astorino@csusm.edu.
authors.forename: Todd Anthony
authors.initials: TA
authors.lastname: Astorino
authors.forename: Eric T
authors.initials: ET
authors.lastname: Harness
authors.forename: Kara A
authors.initials: KA
authors.lastname: Witzke
mesh_terms: D000328:Adult; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging; D024042:Collagen Type I / Q000097:blood; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000097:blood; D011347:Procollagen / Q000097:blood; D011859:Radiography; D013119:Spinal Cord Injuries / Q000097:blood / Q000503:physiopathology / Q000628:therapy*
chemical_list: D024042:Collagen Type I; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide